While out playing in the yard of his mother's employer one day, young Petey Atlas hears screams, races back to the house and there witnesses his mother Linda being terrorized by three thugs. Running away in a state of shock, Petey wanders onto the highway and is picked up by some truckers. Petey is unable to respond to the truckers’ questions, and so they decide to leave him with Jim Warren, the dispatcher at the produce company where they are to make a delivery. Warren notifies the police, who take the boy to headquarters, where Sgt. Paul Denke recognizes him as the son of police detective Tony Atlas. Tony, who is separated from his wife Linda, hurries to the police station, but Petey, still suffering from shock, fails to recognize his own father. Back at the house, meanwhile, Linda’s assailants—Joey Gomez, a dimwitted, hot tempered teen; his friend Gil Rambsy; and Jess Reber, a young tough--squabble over what to do with Linda, who has witnessed Joey bludgeon to death her employer, the elderly Ben Canfield, in an aborted robbery attempt. Although Gil and Jess insist on killing Linda, the only eyewitness to their crime, Joey steadfastly opposes them. At headquarters, Tony briefs the police force about Linda’s disappearance, then goes to search her apartment with Paul. There, Tony discovers that Linda left with Petey early that morning to go to a temporary stenography job. Meanwhile, as Linda pleads with Joey to let her go, Gil and Jess suddenly announce that they have decided to take her with them. Gil then leaves for his mother’s apartment, where he plans to steal his stepfather’s gun. As the investigation continues, Tony learns that some truckers left Petey with Warren at the produce market. The trail reaches a dead end, however, when Warren, who is having an affair, fails to return home to his wife that night. At the house, meanwhile, Canfield’s niece Myra calls, and when Linda answers the phone, Myra becomes suspicious. Eleven hours after Petey was first found, Tony, deducing that Linda may have been an innocent victim of a robbery, decides to expand his investigation into the areas surrounding the produce company. After Tony orders an inquiry into all of the ex-convicts in the vicinity, he confides to Paul his guilt over breaking up his marriage when Linda insisted on working outside the house. Meanwhile, a suspicious Myra drives to her uncle’s house, but when she finds a car in the garage bearing Linda’s identification, she assumes that her uncle is having an affair and drives off. When the police inquiry turns up Jess’s name, they go to his rooming house to interrogate him and there the clerk mentions his friendship with Gil. At Gil’s home, Tony and Paul question Gil’s mother, who lies that her son is not there. Sensing that she is lying, Tony returns to the building and finds Gil climbing out a rear window. Gil starts firing at Tony with his stolen gun, leading him on a chase across the rooftops and into the subway, where Tony shoots and kills him in self-defense. After Tony finds a pile of cash and Linda’s wallet on Gil���s body, he returns to interrogate Gil’s mother, but she knows nothing about her son’s activities. When Warren finally returns home, he puts Tony in contact with the truckers, who remember picking up the boy on a highway near Canfield’s house. The next morning, Jess finds a gun hidden in the house and turns it on Linda. To save her life, Joey jumps Jess and the weapon fires, killing Joey. Tony, meanwhile, takes Peter for a ride along the highway and after the boy suddenly reacts to a tractor outside the Canfield house, realizes that Linda is being held hostage inside. Jess, now paranoid over Gil’s failure to return, spots the police surrounding the house. Just then, Tony kicks down the door and finds Canfield’s dead body. Having retreated to the stairway, Jess points his gun at Linda and orders the police to drop their weapons. Defying him, Tony steadily advances up the stairs, and when Jess turns toward him, an officer fires his revolver, sending Jess scurrying into a room for cover. After cornering Jess, Tony grabs the gun from his hand and then slaps him across the face. Reassuring Linda that Petey is safe, Tony escorts her outside. When she calls to Petey, the boy snaps out of his trance and runs to his mother.